Layout Phase 1 — decomposed components + 8-step pipeline + hybrid Style builder

CHANGELOG.md

@@ -23,3 +23,32 @@ tagged release.
   deferral.
 - `bevy_picking` backend. `Hovered` becomes a thin layer over the standard
   `PointerHits` event flow. Closes the Phase 0 picking deferral.
+- `buiy_core::components::Visual` component (`background_token`,
+  `foreground_token`, `border_radius`) carrying the render-side surface
+  formerly mixed into the Phase 0 mega-`Style`. Authors who want themed
+  widgets insert `Visual` alongside the new layout `Style` builder.
+  Eventual home is `buiy-render-pipeline-design`.
+- `buiy_core::layout` module: 8-step layout pipeline (`BuiyLayoutStep`
+  system sets), decomposed `BoxModel` / `Display` / `Position` /
+  `FlexParams` / `FlexItem` components, hybrid `Style` builder that
+  expands to a `Bundle` on spawn.
+
+### Changed
+- Layout subsystem foundation rewritten. Phase 0's flat `layout.rs` is
+  replaced by a `layout/` directory module. The pipeline is an 8-step
+  ordered chain (`BuiyLayoutStep` system sets) inside `BuiySet::Layout`;
+  Phase 1 implements steps 0/1/3/7 and stubs the remaining four for
+  later phase plans.
+- `Style` is now a `Bundle` that decomposes on insert, not a reflectable
+  `Component`. Reflection / inspectors / BSN see the decomposed
+  components (`BoxModel`, `Display`, `Position`, `FlexParams`).
+- The render extract now queries `(&Visual, &ResolvedLayout)` instead
+  of `(&Style, &ResolvedLayout)`; entities without `Visual` are skipped
+  by render. `Button::new` inserts a `Visual` carrying the same theme
+  tokens Phase 0's `Style` did, so visual appearance is preserved.
+
+### Removed
+- `buiy_core::components::Style` (the Phase 0 mega-component) and
+  `buiy_core::components::FlexDirection`. Their roles are taken by
+  `buiy_core::layout::Style` (the hybrid builder) and
+  `buiy_core::layout::FlexAxis` (the four-variant axis enum).

crates/buiy/src/lib.rs

@@ -7,8 +7,13 @@ use bevy::prelude::*;
 pub use buiy_core::{
     BuiySet, CorePlugin,
     a11y::{A11yDescription, A11yLabel, A11yRole, A11yTreeBuilder, AccessKitAdapterPlugin},
-    components::{FlexDirection, Node, ResolvedLayout, Style},
+    components::{Node, ResolvedLayout, Visual},
     focus::{FocusVisible, Focusable, FocusedEntity},
+    layout::{
+        AlignContent, AlignItems, AspectRatio, BoxModel, BoxSizing, BuiyLayoutStep, Display, Edges,
+        FlexAxis, FlexGap, FlexItem, FlexParams, FlexWrap, Inset, JustifyContent, LayoutPlugin,
+        Length, Position, PositionKind, Sizing, Style,
+    },
     picking::{BuiyPickingBackendPlugin, Hovered},
     theme::{Theme, UserPreferences, default_light_theme},
 };

crates/buiy_core/src/components.rs

@@ -1,57 +1,24 @@
 //! Buiy's core component types.
 //!
-//! Every Buiy component is small, public-fielded, observable, and decomposed
-//! by concern. Every component derives `Reflect + Default + Clone + Component`
-//! (and Bevy 0.18's `Reflect` derive auto-generates `FromReflect`). See:
-//! docs/specs/2026-05-07-buiy-foundation/architecture.md § 2.4.
+//! Every Buiy component is small, public-fielded, observable, and
+//! decomposed by concern. Layout components live in
+//! `crate::layout::components`; this file holds the cross-cutting
+//! `Node` marker, the shared `ResolvedLayout` output, and the temporary
+//! `Visual` component (token-based rendering surface — eventual owner
+//! is `buiy-render-pipeline-design`).
+//!
+//! See: docs/specs/2026-05-07-buiy-foundation/architecture.md § 2.4.
 
 use bevy::prelude::*;
 
-/// Flex layout direction. Mirrors Taffy's `FlexDirection` for the
-/// row / column subset used in Phase 0; v0.x layout-design will widen
-/// this to include `RowReverse` / `ColumnReverse` when needed.
-///
-/// Marked `#[non_exhaustive]` because new variants are expected pre-1.0
-/// and external matches must opt in to handling them.
-#[derive(Reflect, Default, Clone, Copy, Debug, PartialEq, Eq)]
-#[non_exhaustive]
-pub enum FlexDirection {
-    #[default]
-    Row,
-    Column,
-}
-
-/// A Buiy node — the parallel-to-bevy_ui::Node primitive. Marker that this
-/// entity participates in Buiy's layout / render / a11y trees.
+/// A Buiy node — the parallel-to-`bevy_ui::Node` primitive. Marker that
+/// this entity participates in Buiy's layout / render / a11y trees.
 #[derive(Component, Reflect, Default, Clone, Debug)]
 #[reflect(Component)]
 pub struct Node;
 
-/// Box-model + layout style. Not exhaustive in Phase 0 — only the surface
-/// the layout system reads.
-#[derive(Component, Reflect, Default, Clone, Debug)]
-#[reflect(Component)]
-pub struct Style {
-    /// Width in logical pixels. 0.0 = auto.
-    pub width: f32,
-    /// Height in logical pixels. 0.0 = auto.
-    pub height: f32,
-    /// Padding on all sides.
-    pub padding: f32,
-    /// Margin on all sides.
-    pub margin: f32,
-    /// Border radius (uniform; per-corner is a later sub-spec).
-    pub border_radius: f32,
-    /// Flex direction. Mapped to Taffy in `layout.rs`.
-    pub flex_direction: FlexDirection,
-    /// Token reference for background color (e.g., "color.surface.primary").
-    pub background_token: String,
-    /// Token reference for foreground/text color.
-    pub foreground_token: String,
-}
-
-/// Resolved layout output, written by the layout system in `BuiySet::Layout`.
-/// Read by render and picking in subsequent sets.
+/// Resolved layout output, written by `BuiyLayoutStep::WriteResolvedLayout`.
+/// Read by render, picking, and any other downstream subsystem.
 #[derive(Component, Reflect, Default, Clone, Debug)]
 #[reflect(Component)]
 pub struct ResolvedLayout {
@@ -60,3 +27,27 @@ pub struct ResolvedLayout {
     /// Size in logical pixels.
     pub size: Vec2,
 }
+
+/// Visual surface: theme-token references and corner radius for the
+/// Phase 0/1 render pipeline. Optional — entities without `Visual` are
+/// skipped by the render extract.
+///
+/// **Temporary home.** This is a Phase 0 carry-over, kept alive in
+/// Phase 1 only because the render extract still consumes
+/// `background_token` / `border_radius`. The eventual owner of these
+/// concerns is `buiy-render-pipeline-design` (unwritten as of Phase 1);
+/// when that spec lands, `Visual` is replaced by richer
+/// `Background` / `Border` / `Stroke` / etc. components.
+#[derive(Component, Reflect, Default, Clone, Debug)]
+#[reflect(Component)]
+pub struct Visual {
+    /// Theme token for the fill (e.g. `"color.surface.secondary"`).
+    /// Empty string → render skips the fill (transparent).
+    pub background_token: String,
+    /// Theme token for foreground / text color (e.g. `"color.text.primary"`).
+    /// Reserved for the text-rendering integration; Phase 1 render does
+    /// not consume it.
+    pub foreground_token: String,
+    /// Uniform corner radius in logical pixels.
+    pub border_radius: f32,
+}